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Chen PZ, Bobrovitz N, Premji Z, Koopmans M, Fisman DN, Gu FX. Heterogeneity in transmissibility and shedding SARS-CoV-2 via droplets and aerosols. eLife 2021; 10:e65774. [PMID: 33861198 PMCID: PMC8139838 DOI: 10.7554/elife.65774] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/15/2021] [Indexed: 01/08/2023] Open
Abstract
Background Which virological factors mediate overdispersion in the transmissibility of emerging viruses remains a long-standing question in infectious disease epidemiology. Methods Here, we use systematic review to develop a comprehensive dataset of respiratory viral loads (rVLs) of SARS-CoV-2, SARS-CoV-1 and influenza A(H1N1)pdm09. We then comparatively meta-analyze the data and model individual infectiousness by shedding viable virus via respiratory droplets and aerosols. Results The analyses indicate heterogeneity in rVL as an intrinsic virological factor facilitating greater overdispersion for SARS-CoV-2 in the COVID-19 pandemic than A(H1N1)pdm09 in the 2009 influenza pandemic. For COVID-19, case heterogeneity remains broad throughout the infectious period, including for pediatric and asymptomatic infections. Hence, many COVID-19 cases inherently present minimal transmission risk, whereas highly infectious individuals shed tens to thousands of SARS-CoV-2 virions/min via droplets and aerosols while breathing, talking and singing. Coughing increases the contagiousness, especially in close contact, of symptomatic cases relative to asymptomatic ones. Infectiousness tends to be elevated between 1 and 5 days post-symptom onset. Conclusions Intrinsic case variation in rVL facilitates overdispersion in the transmissibility of emerging respiratory viruses. Our findings present considerations for disease control in the COVID-19 pandemic as well as future outbreaks of novel viruses. Funding Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant program, NSERC Senior Industrial Research Chair program and the Toronto COVID-19 Action Fund.
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Affiliation(s)
- Paul Z Chen
- Department of Chemical Engineering & Applied Chemistry, University of TorontoTorontoCanada
| | - Niklas Bobrovitz
- Temerty Faculty of Medicine, University of TorontoTorontoCanada
- Department of Critical Care Medicine, Cumming School of Medicine, University of CalgaryCalgaryCanada
- O'Brien Institute of Public Health, University of CalgaryCalgaryCanada
| | - Zahra Premji
- Libraries & Cultural Resources, University of CalgaryCalgaryCanada
| | - Marion Koopmans
- Department of Viroscience, Erasmus University Medical CenterRotterdamNetherlands
| | - David N Fisman
- Division of Epidemiology, Dalla Lana School of Public Health, University of TorontoTorontoCanada
- Division of Infectious Diseases, Temerty Faculty of Medicine, University of TorontoTorontoCanada
| | - Frank X Gu
- Department of Chemical Engineering & Applied Chemistry, University of TorontoTorontoCanada
- Institute of Biomedical Engineering, University of TorontoTorontoCanada
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Lalueza A, Folgueira D, Muñoz-Gallego I, Trujillo H, Laureiro J, Hernández-Jiménez P, Moral-Jiménez N, Castillo C, Ayuso B, Díaz-Pedroche C, Torres M, Arrieta E, Arévalo-Cañas C, Madrid O, Lumbreras C. Influence of viral load in the outcome of hospitalized patients with influenza virus infection. Eur J Clin Microbiol Infect Dis 2019; 38:667-673. [PMID: 30820840 PMCID: PMC7102091 DOI: 10.1007/s10096-019-03514-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 02/14/2019] [Indexed: 01/30/2023]
Abstract
The role of viral load in the outcome of patients requiring hospital admission due to influenza is not well established. We aim to assess if there is an association between the viral load and the outcome in hospitalized patients with a confirmed influenza virus infection. A retrospective observational study including all adult patients who were hospitalized in our center with a confirmed influenza virus infection from January to May 2016. Viral load was measured by real-time reverse-transcriptase–polymerase chain reaction (rRT-PCR) cycle threshold (Ct) value on upper respiratory tract samples. Its value was categorized into three groups (low Ct, ≤ 20; intermediate Ct, > 20–30; and high Ct, > 30). Two hundred thirty-nine patients were included. Influenza A/H1N1pdm09 was isolated in 207 cases (86.6%). The mean Ct value was 26.69 ± 5.81. The viral load was higher in the unvaccinated group when compared with the vaccinated patients (Ct 25.17 ± 5.55 vs. 27.58 ± 4.97, p = 0.004). Only 27 patients (11.29%) presented a high viral load. Patients with a high viral load more often showed abnormal findings on chest X-ray (p = 0.015) and lymphopenia (p = 0.097). By contrast, there were no differences between the three groups (according to viral load), in associated pneumonia, respiratory failure, need for mechanical ventilation, sepsis, or in-hospital mortality. Our findings suggest that in patients admitted to the hospital with confirmed influenza virus infection (mostly A/H1N1pdm09), a high viral load is associated with a higher presence of abnormal findings on chest X-ray but not with a significant worse prognosis. In these cases, standardized quantitative PCR could be useful.
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Affiliation(s)
- Antonio Lalueza
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain. .,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain. .,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.
| | - Dolores Folgueira
- Department of Medicine, School of Medicine, Complutense University, Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Department of Microbiology, University Hospital 12 de Octubre, Madrid, Spain
| | - Irene Muñoz-Gallego
- Department of Microbiology, University Hospital 12 de Octubre, Madrid, Spain
| | - Hernando Trujillo
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Jaime Laureiro
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Pilar Hernández-Jiménez
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | | | - Cristina Castillo
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Blanca Ayuso
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Carmen Díaz-Pedroche
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain.,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain
| | - Marta Torres
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Estibaliz Arrieta
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Coral Arévalo-Cañas
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Olaya Madrid
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain
| | - Carlos Lumbreras
- Department of Internal Medicine, University Hospital 12 de Octubre, Av. Córdoba km 5400, 28041, Madrid, Spain.,Department of Medicine, School of Medicine, Complutense University, Madrid, Spain.,Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, Spain.,Infectious Diseases Unit, University Hospital 12 de Octubre, Madrid, Spain
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Van Wesenbeeck L, D'Haese D, Tolboom J, Meeuws H, Dwyer DE, Holmes M, Ison MG, Katz K, McGeer A, Sadoff J, Weverling GJ, Stuyver L. A Downward Trend of the Ratio of Influenza RNA Copy Number to Infectious Viral Titer in Hospitalized Influenza A-Infected Patients. Open Forum Infect Dis 2015; 2:ofv166. [PMID: 26677457 PMCID: PMC4680923 DOI: 10.1093/ofid/ofv166] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/07/2015] [Indexed: 01/02/2023] Open
Abstract
Background. Efficacy endpoints in influenza clinical trials may include clinical symptoms and virological measurements, although virology cannot serve as the primary endpoint. We investigated the relationship between influenza A RNA copy number and quantity of infectious viruses in hospitalized influenza patients. Methods. One hundred fifty influenza-infected, hospitalized patients were included in this prospective cohort study spanning the 2012-2013 influenza season. Daily nasopharyngeal samples were collected during hospitalization, and influenza A RNA copy number and infectious viral titer were monitored. Results. The decay rate for 50% tissue culture infectious dose (TCID50) was 0.51 ± 0.14 log10 TCID50/mL per day, whereas the RNA copy number decreased at a rate of 0.41 ± 0.04 log10 copies/mL per day (n = 433). The log ratio of the RNA copy number to the infectious viral titer within patient changes significantly with -0.25 ± 0.09 units per day (P = .0069). For a 12-day observation period, the decay corresponds to a decline of this ratio of 3 log influenza RNA copies. Conclusions. Influenza RNA copy number in nasal swabs is co-linear with culture, although the rate of decay of cell culture-based viral titers was faster than that observed with molecular methods. The study documented a clear decreasing log ratio of the RNA copy number to the infectious viral titer of the patients over time.
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Affiliation(s)
| | | | | | | | | | | | - Michael G Ison
- Northwestern University Feinberg School of Medicine , Chicago, Illinois
| | | | - Allison McGeer
- Department of Microbiology , Mount Sinai Hospital , Toronto , Canada
| | - Jerald Sadoff
- Janssen Infectious Diseases , Leiden , The Netherlands
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Echenique IA, Chan PA, Chapin KC, Andrea SB, Fava JL, Mermel LA. Clinical characteristics and outcomes in hospitalized patients with respiratory viral co-infection during the 2009 H1N1 influenza pandemic. PLoS One 2013; 8:e60845. [PMID: 23585856 PMCID: PMC3622008 DOI: 10.1371/journal.pone.0060845] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 03/05/2013] [Indexed: 12/16/2022] Open
Abstract
Background The clinical consequences of co-infection with two or more respiratory viruses are poorly understood. We sought to determine if co-infection with pandemic 2009–2010 influenza A H1N1 (pH1N1) and another respiratory virus was associated with worse clinical outcomes. Methods A retrospective cohort study was performed of all hospitalized patients with a positive respiratory viral panel (RVP) for two or more viruses within 72 hours of admission at our institution from October 2009 to December 2009. We compared patients infected with one respiratory virus to those with respiratory viral co-infection. Results We identified 617 inpatients with a positive RVP sample with a single virus and 49 inpatients with a positive RVP sample for two viruses (i.e. co-infection). Co-infected patients were significantly younger, more often had fever/chills, tachypnea, and they more often demonstrated interstitial opacities suggestive of viral pneumonia on the presenting chest radiograph (OR 7.5, 95% CI 3.4–16.5). The likelihood of death, length of stay, and requirement for intensive care unit level of care were similar in both groups, but patients with any respiratory virus co-infection were more likely to experience complications, particularly treatment for a secondary bacterial pneumonia (OR 6.8, 95% CI 3.3–14.2). Patients co-infected with pH1N1 and another respiratory virus were more likely to present with chest radiograph changes suggestive of a viral pneumonia, compared to mono-infection with pH1N1 (OR 16.9, 95% CI 4.5–62.7). By logistic regression using mono-infection with non-PH1N1 viruses as the reference group, co-infection with pH1N1 was the strongest independent predictor of treatment for a secondary bacterial pneumonia (OR 17.8, 95% CI 6.7–47.1). Conclusion Patients with viral co-infection, particularly with pH1N1, were more likely to have chest radiograph features compatible with a viral pneumonia and complications during their hospital course, particularly treatment for secondary bacterial pneumonia. Despite this, co-infection was not associated with ICU admission.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Antiviral Agents/therapeutic use
- Child
- Child, Preschool
- Coinfection
- Female
- Hospitalization
- Humans
- Infant
- Influenza A Virus, H1N1 Subtype
- Influenza, Human/diagnostic imaging
- Influenza, Human/epidemiology
- Influenza, Human/pathology
- Influenza, Human/therapy
- Intensive Care Units
- Male
- Middle Aged
- Pandemics
- Picornaviridae Infections/diagnostic imaging
- Picornaviridae Infections/epidemiology
- Picornaviridae Infections/pathology
- Picornaviridae Infections/therapy
- Pneumonia, Bacterial/diagnostic imaging
- Pneumonia, Bacterial/epidemiology
- Pneumonia, Bacterial/pathology
- Pneumonia, Bacterial/therapy
- Radiography
- Retrospective Studies
- Rhode Island/epidemiology
- Treatment Outcome
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Affiliation(s)
- Ignacio A. Echenique
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Philip A. Chan
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Division of Infectious Diseases, Rhode Island Hospital, Providence, Rhode Island, United States of America
| | - Kimberle C. Chapin
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Department of Pathology, Rhode Island Hospital, Providence, Rhode Island, United States of America
| | - Sarah B. Andrea
- Department of Pathology, Rhode Island Hospital, Providence, Rhode Island, United States of America
| | - Joseph L. Fava
- Centers for Behavioral and Preventive Medicine, The Miriam Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Leonard A. Mermel
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Division of Infectious Diseases, Rhode Island Hospital, Providence, Rhode Island, United States of America
- * E-mail:
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